Cobra venom factor (CVF) is a 136 kDa molecular mass glycoprotein that is capable of activating the complement system via the alternate pathway. It contains four to five N-linked oligosaccharide chains per molecule, which are essential for its function. We are studying the structures of the N-linked oligosaccharides of CVF from Naja naja siamensis. The combination of results obtained through NMR spectroscopy and FAB-mass spectrometry in our laboratory with the results of lectin affinity chromatography and exoglycosidase digestion of radiolabeled glycopeptides in Dr. Gowda's lab led to the conclusion that the oligosaccharides from CVF are di- and triantennary N-acetyllactosamine-type structures ending in Gal?(1?3)Gal?(1?4)[Fuc?(1?3)]GlcNAc?(1?). Other structures include tri- or tetraantennary N-glycans as well as high-mannose structures. A manuscript is in preparation describing this work.